Part number help....

[William D.]

I finally figured out where the part numbers are on the A/C vacuum actuators and would like help with replacement part numbers for the following actuators:

GM# 1998958 - Heater core box vacuum actuator with A/C

GM# 1998965 - Defroster box vacuum actuator with A/C

Thanks,
Bill

[David L.]

Re: Part number help....

Bill,

Where did you get the part numbers 1998958 (ELEMENT for 69 Pass. w/C.A.C. in Gr. 9.281) and 1998965? The actuators listed for the 69 Corvette w/AC are GM # 1998944 and 1998961 in Gr. 9.281 in my 1969 Corvette Parts Catalog (Sept. 1969) and my 1969 Chevrolet Parts Catalog (Oct. 1968), see photo below.

According to Chevrolet Parts History GM # 1998958 was replaced with 1998991 in November 1970 and GM # 1998965 was replaced with GM # 1998991 in Jan. 1971.

GM # 1998991 was then replaced with GM # 1998999 in Jan. 1973.

GM # 1998999 was available for $8.40 (list) in Dec. 1981 as per my 1982 Chev. Price Schedule.
GM # 1998999 is listed as an "ACTUATOR, HTR AIR DIST VAC" in my 1982 Corvette Parts Catalog (Nov. 1981) for 69-77 Corvettes w/AC.
GM # 1996607 is listed as an "ACTUATOR, AIR INLET PLENUM VLV" for 69-81 Corvettes w/AC.

Abbreviated part # history:
1998944 to 1996503 to 1996607 then discontinued.
1998961 to 1998990 to 1996505 to 1996608 then discontinued.

Good luck in your search

Dave

[William D.]

Re: Part number help....

Hi Dave,

Thanks for the response.
There are four (4) vacuum actuators in the heating/AC system.

One is the air inlet side shroud actuator GM# 1998961. This actuator
is mounted in the top right side of the car in the wiper area.

One is the air inlet plenum actuator GM# 1998944. This actuator is
mounted in front of the speaker inside the car on the passenger side.

One is the selector box actuator (resides in the heater core box)
GM# 1998965 (this is what was in my car). This actuator is mounted on the left hand side of the heater core (selector box Assembly).

One is the distribution box actuator GM# 1998958 (this is what was in my
car). This actuator is mounted on the left hand side of the defrost box.

I hope that the above clears up my initial posting.

From the info that you provided it looks as though 1998991 or 1998999 will work for both applications.

The disappointing thing with these actuators is that the diaphragms on both of my actuators are leak free. It's the shaft seal that has deteriorated on both of them.

Thanks for your help.

Bill